Amusement parks are experiencing an ever-increasing success in both the United States, where they originated, and the rest of the world. One of the most spectacular and most impressive attractions is that known by the name “roller coaster”. These roller coasters comprise one or more vehicles constituting a train, running on a guide track, generally the rails of a circuit, with steeply sloping portions of circuit. The passengers have a liking for this attraction for the strong impressions it gives. These impressions result to a great extent from the various sensations of acceleration given by the route; they also result from subjective impressions, namely feelings of vertigo, fear, illusion of the risk or surprise faced with the appearance of unexpected events, which the constructor tries to generate through the arrangement of the circuit.
The U.S. Pat. No. 3,167,024 describes a roller coaster installation simulating a bobsleigh run, comprising a pool of water towards the end of the circuit, before the entry to the station. The rails cross the pool, under the surface of the water. The streamlined lower part of the vehicles enters the water during the crossing of the pool, which brakes them whilst raising a spray of water. This installation has several drawbacks: at the moment of the entry of the vehicle into the water, a shock is almost inevitable; at this moment and during the crossing of the pool, the resistance of the water exerts a force which has a large vertical component on the vehicle, which tends to separate the latter from the rails and which must be compensated for by the components of the undercarriage. The mechanical stresses to which the undercarriage is subjected are therefore particularly great with this system. The contact with the water tends to remove lubricating material from the bearings. The repeated shocks, as well as the corrosion due to frequent passing between water and air, tends to cause rapid wear of the undercarriage. In addition, at the slightest sealing defect of the body, the passengers in the vehicle risk being soaked.
The patent CH 689857 of the applicant and the application DE 10160039 describe circuits which pass into a stretch of water, arranged so as to give the passengers an impression of splash-down. The level of the railway line in the stretch of water is below the water level. On account of the vehicles being designed to remain fixed to the rails, these vehicles are then partially submerged in the water, which causes on the one hand considerable braking and on the other hand large sprays of water. This section is followed by a small ramp in order to bring the train of vehicles to the level of the station. These circuits also pose the problems related to a specific design of vehicle having to withstand a very large number of entries in contact with the water in the pool.